分级真空预压法加固吹填土过程中孔隙分布特征

针对实际工程中吹填土自重固结时间过长和真空预压加固过程中排水管容易淤堵、固结、速度减慢的问题，提出了分级真空预压即逐级施加真空荷载的加固方案，进行了室内模拟试验。试验结果表明：吹填土在固结过程中含水率逐渐减小，易溶盐含量逐渐减小，土体强度逐渐增大，吹填土的物理化学性质得到改善，土体固结效果较均匀；同时对吹填土固结过程中取样进行压汞试验，利用分形理论划分了吹填土孔隙分布区间。探讨了固结过程中孔隙分布特征的变化规律：随着固结压力的增加，吹填土中超大孔隙和大孔隙先被压缩成中孔隙，中孔隙再被压缩成小孔隙；孔径分布由大孔隙集中分布(占50%以上)向中孔隙(占35%以上)和小孔隙(占35%以上)发展。

Pore Distribution Characteristics of Dredger Fill During Hierarchical Vacuum Preloading

In view of the problems such as the time of self-consolidation is long and the drain pipes are easy to clogged and consolidation will slow down gragually in practice,a grading vacuum preloading method is put forward,namely,vacuum preloading is imposed hierarchically,and simulation tests are carried out in laboratory.The test results show that the moisture content and the soluble salt content decreases gradually,the strength increases gradually during the consolidation process of dredger fill.The physical and chemical properties of dredger fill have been improved after the hierarchical vacuum preloading.At the same time,samples are tested by the mercury intrusion test which sampled from consolidation process and the pore distribution characteristics is analyzed by using fractal theory.It shows that the large size of pore will be compressed into more small pore with the increase of consolidation pressure and the variation of pore diameter distribution is changed from majority of large size pore(above 50%) into advantage of middle and small size pore,which are above 35% and above 35% respectively.